Blood Diamond stars Leonardo DiCaprio as a diamond smuggler in the west African nation of Sierra Leone during its civil war in the 1990s.

At a press conference, Mr Zwick pointed out "the cruel irony... that the raising of one's hand and the using of one's hand to vote was the prompt for the Revolutionary United Front to chop off hands in Sierra Leone".

"It's either some colossal cluelessness or remarkable indifference to that reality that would somehow try to equate raising one's hand with a diamond on it as a promotional counter-measure to the effect of the film," he said.

The film-maker said he believed charity was "best done in private".

He called the Raise Your Right Hand Ring for Africa campaign a "charitable bribe", adding: "I find that rather distasteful, I have to say."

'Unfortunate connection'

DIC director Sally Morrison said the campaign was not a response to the film.

For a number of years, major jewellers had been making charity donations in return for stars wearing their merchandise at awards ceremonies, she said.

"It's sort of strange that someone who is apparently so concerned about the needs of Africans is making public statements to stop jewellers from making large amounts of money available to African charities," she said.

"It's unfortunate because it may be that people hear this and hear this very unfortunate connection that has been constructed, and decide not to do it.

"The people who would be hurt by that are the beneficiaries of the charities."

'Havoc'

The World Diamond Council (WDC) said so-called "blood diamonds" made up less than 1% of new diamonds, compared with 4% in the late 1990s.

This follows the introduction in 2000 of a certification system for rough diamonds - the Kimberley Process.

But campaign group Global Witness claims the industry has not done enough, saying: "Even a small percentage can wreak havoc.

"Wars funded by diamonds have been devastating - they have claimed hundreds of thousands of lives, they have displaced millions of people, atrocities have been committed."

Conflict diamonds have been linked to armed struggles in Sierra Leone, Liberia, the Democratic Republic of Congo and the Central African Republic.